I phoned this well known place in my city and gave very little answers
Don't let you watch, don't let you try it. 2 months or nothing. Couldn't give a rough number, of the number of students in the class, what is covered, nothing.

So, what would I be looking at for the beginner class? Should I bring water bottle? How many times a week should I go?
They said there are two kickboxing classes, two muay thai classes, and one cardio kickboxing class. What do most people do? Once a week? twice? three? What's the point of going multiple times a week? Conditioning and practice?

strange that they didn't give any info and at least one trial class.
there is too many different thing that could make going there for 2 month not very pleasurable - bad teachers, too many people in the class, too many noobish people in the class, not enough room, not challenging or just not interesting.

otherwise, water will help for sure but you will see yourself how many times you are able to go and what lessons to take.
i for example can't go more than 3 times a week usually 2 - classes are super hard and i work very hard too, takes a lot of time to recover plus personal life

That is very weird. The place I train allows a free class first to try it first hand and you could just watch if you wanted. That just sounds weird and kind of fishy to me, like they are trying to rip you off or something. I dont know.

I agree it does sound kind of weird, how much will they charge for a 2 month membership? I would suggest either going in and requesting that you trial a class (usually $20) or re-calling and requesting to speak to the instructor if you only spoke to the receptionist or something and asking them your questions. If they refuse to allow you to participate in a trial lesson then don't bother with them and try another place.

I've just started Muay Thai within the last month. My experience, the school let me take a free lesson (how the hell are you supposed to know if it's for you or not?) and I enjoyed it so much that I signed up right after class. It cost me $390, which included a $99 one time sign up fee, the first month and mouth guard, hand wraps, King boxing gloves, t shirt and combo manual.

The first lesson, be prepared to WORK. I play hockey in a rec league and I've been so short benched that I was forced to play for 40 minutes without subbing...and even that was nothing compared to the workout you'll get from Muay Thai. Expect to feel like a tool for awhile until you start to get used to the movements a little bit, expect to sweat and be dogged tired. I go 2 times a week for roughly an hour, but once I start to feel more comfortable with technique and stuff, I might go more often (I can go pretty much every day of the week and there'll be a lesson).

Y'know what, I wouldn't join the school you just mentioned, what's with the secrecy? Find a school with a trial class and give it a shot, I know I love it...and I'm usually a lazy bastard.